Objective
Different studies have demonstrated that neutrophil extracellular traps (NETs) may be involved in the pathophysiology of both antineutrophil cytoplasmic antibody (ANCA)–associated ...vasculitis (AAV) and systemic lupus erythematosus (SLE). AAV and SLE are clinically and pathologically divergent autoimmune diseases with different autoantibodies. However, the respective autoantigens recognized in AAV and SLE have been shown to be an intricate part of NETs. This study aimed to examine whether the mechanisms of NET formation and the composition of NETs are distinct between AAV and SLE.
Methods
To investigate this hypothesis, healthy neutrophils were stimulated with serum from patients with AAV (n = 80) and patients with SLE (n = 59), and the mechanisms of NET formation and NET composition were compared.
Results
Both patients with AAV and patients with SLE had excessive NET formation, which correlated with the extent of disease activity (in AAV r = 0.5, P < 0.0001; in SLE r = 0.35, P < 0.01). Lytic NET formation over several hours was observed in patients with AAV, as compared to rapid (within minutes), non‐lytic NET formation coinciding with clustering of neutrophils in patients with SLE. AAV‐induced NET formation was triggered independent of IgG ANCAs, whereas SLE immune complexes (ICx) induced NET formation through Fcγ receptor signaling. AAV‐induced NET formation was dependent on reactive oxygen species and peptidyl arginine deaminases, and AAV‐induced NETs were enriched for citrullinated histones (mean ± SEM 23 ± 2%). In contrast, SLE‐induced NETs had immunogenic properties, including binding with high mobility group box chromosomal protein 1 (mean ± SEM 30 ± 3%) and enrichment for oxidized mitochondrial DNA, and were involved in ICx formation.
Conclusion
The morphologic features, kinetics, induction pathways, and composition of excessive NET formation are all intrinsically distinct in AAV compared to SLE. Recognizing the diversity of NET formation between AAV and SLE provides a better understanding of the pathophysiologic role of NETs in these different autoimmune diseases.
IL‐35 is a cytokine of the IL‐12 family, existing as a heterodimer of IL‐12p35 and Ebi3. IL‐35 has anti‐inflammatory properties and is produced by regulatory T cells in humans and mice, where it is ...required for optimal suppression of immune responses. Distinct from other IL‐12 cytokines, the expression of IL‐35 has not been described in antigen‐presenting cells. In view of the immune‐regulatory properties of IL‐35, we investigated the expression, regulation, and function of IL‐12p35 and Ebi3 in human monocyte‐derived dendritic cells and tolerogenic DCs (tolDCs). These tolDCs do not produce IL‐12p70 or the homodimer IL‐12p40. We demonstrate that tolDCs completely lack transcriptional expression of IL‐12p40. However, tolDCs maintain mRNA expression of IL‐12p35 and Ebi3. Using intracellular flow cytometry and Western blot analysis, we show that tolDCs produce Ebi3 and IL‐12p35, and both can be enhanced upon stimulation with IFN‐γ, LPS, or CD40L. tolDCs supernatants have the capacity to suppress T‐cell activation. Using IL12A silencing, we demonstrate that IL‐12p35 is required for tolDCs to reach their full suppressive potential. Taken together, our results indicate that tolDCs produce IL‐35, providing an additional novel mechanism by which tolDCs elicit their tolerogenic potential.
CD40-CD40 ligand Kooten, Cees; Banchereau, Jacques
Journal of leukocyte biology,
01/2000, Letnik:
67, Številka:
1
Journal Article
Recenzirano
CD40 is a cell surface receptor that belongs to the tumor necrosis factor‐R (TNF‐R) family, and that was first identified and functionally characterized on B lymphocytes. Its critical role in T ...cell‐dependent humoral immune responses was demonstrated by patients with the hyper‐IgM syndrome, as well as by gene targeting in mice. However, in recent years it has become clear that CD40 is expressed much more broadly, including expression on monocytes, dendritic cells, endothelial cells, and epithelial cells. In addition, the CD40‐ligand (CD40‐L/CD154), a member of the TNF family, is also expressed more widely than activated CD4+ T cells only. Therefore it is now thought that CD40‐CD40‐L interactions play a more general role in immune regulation. Collectively these studies have culminated in pre‐clinical and clinical studies that are in progress. This article reviews recent developments in this field of research, with main emphasis on (1) structure and expression of CD40 and its ligand; (2) CD40 signal transduction; (3) in vitro function of CD40 on different cell types; and (4) in vivo functions of CD40/CD40‐L interactions. J. Leukoc. Biol. 67: 2–17; 2000.
After renal transplantation, there is a need for immunosuppressive regimens which effectively prevent allograft rejection, while preserving renal function and minimizing side effects. From this ...perspective, mesenchymal stromal cell (MSC) therapy is of interest. In this randomized prospective, single‐center, open‐label trial, we compared MSCs infused 6 and 7 weeks after renal transplantation and early tacrolimus withdrawal with a control tacrolimus group. Primary end point was quantitative evaluation of interstitial fibrosis in protocol biopsies at 4 and 24 weeks posttransplant. Secondary end points included acute rejection, graft loss, death, renal function, adverse events, and immunological responses. Seventy patients were randomly assigned of which 57 patients were included in the final analysis (29 MSC; 28 controls). Quantitative progression of fibrosis failed to show benefit in the MSC group and GFR remained stable in both groups. One acute rejection was documented (MSC group), while subclinical rejection in week 24 protocol biopsies occurred in seven patients (four MSC; three controls). In the MSC group, regulatory T cell numbers were significantly higher compared to controls (p = .014, week 24). In conclusion, early tacrolimus withdrawal with MSC therapy was safe and feasible without increased rejection and with preserved renal function. MSC therapy is a potentially useful approach after renal transplantation.
TRITON, a randomized, prospective, single‐center, open‐label study, shows that autologous mesenchymal stromal cell therapy and early tacrolimus withdrawal was feasible and safe, without increased rejection and with preserved renal function.
Mesenchymal stromal cells (MSC) hold promise as a novel immune‐modulatory therapy in organ transplantation. First clinical studies have used autologous MSCs; however, the use of allogeneic ..."off‐the‐shelf" MSCs is more sustainable for broad clinical implementation, although with the risk of causing sensitization. We investigated safety and feasibility of allogeneic MSCs in renal transplantation, using a matching strategy that prevented repeated mismatches. Ten patients received two doses of 1.5 × 106/kg allogeneic MSCs 6 months after transplantation in a single‐center nonrandomized phase Ib trial, followed by lowering of tacrolimus (trough level 3 ng/mL) in combination with everolimus and prednisone. Primary end point was safety, measured by biopsy proven acute rejection (BPAR) and graft loss 12 months after transplantation. Immune monitoring was performed before and after infusion. No BPAR or graft loss occurred and renal function remained stable. One patient retrospectively had DSAs against MSCs, formed before infusion. No major alterations in T and B cell populations or plasma cytokines were observed upon MSC infusion. Administration of HLA selected allogeneic MSCs combined with low‐dose tacrolimus 6 months after transplantation is safe at least in the first year after renal transplantation. This sets the stage to further explore the efficacy of third‐party MSCs in renal transplantation.
The authors report that administration 6 months after kidney transplantation of allogeneic bone marrow–derived mesenchymal stromal cells selected to have no repeated HLA mismatches with the kidney donor was safe 1 year after transplantation with no instances of biopsy‐proven acute rejection, graft loss, or de novo antibodies against either donor.
The bioengineering of a replacement kidney has been proposed as an approach to address the growing shortage of donor kidneys for the treatment of chronic kidney disease. One approach being ...investigated is the recellularization of kidney scaffolds. In this study, we present several key advances toward successful re‐endothelialization of whole kidney matrix scaffolds from both rodents and humans. Based on the presence of preserved glycosoaminoglycans within the decelullarized kidney scaffold, we show improved localization of delivered endothelial cells after preloading of the vascular matrix with vascular endothelial growth factor and angiopoietin 1. Using a novel simultaneous arteriovenous delivery system, we report the complete re‐endothelialization of the kidney vasculature, including the glomerular and peritubular capillaries, using human inducible pluripotent stem cell –derived endothelial cells. Using this source of endothelial cells, it was possible to generate sufficient endothelial cells to recellularize an entire human kidney scaffold, achieving efficient cell delivery, adherence, and endothelial cell proliferation and survival. Moreover, human re‐endothelialized scaffold could, in contrast to the non‐re‐endothelialized human scaffold, be fully perfused with whole blood. These major advances move the field closer to a human bioengineered kidney.
Human decellularized kidney scaffolds can be functionally re‐endothelialized using expanded human pluripotent stem cell–derived endothelial cells.
Mesenchymal stromal cells (MSCs) are an interesting candidate to aid in the long‐term survival of transplanted kidneys, because of their immunosuppressive and regenerative properties. This phase I ...study was the first to investigate the effects of MSCs in allograft rejection and fibrosis. Findings support the potential of MSCs as a novel cell therapy to prevent allograft rejection and interstitial fibrosis/tubular atrophy. The observed systemic immune suppression implies that careful monitoring of opportunistic viral infection is needed.
Despite excellent short‐term results, long‐term survival of transplanted kidneys has not improved accordingly. Although alloimmune responses and calcineurin inhibitor‐related nephrotoxicity have been identified as main drivers of fibrosis, no effective treatment options have emerged. In this perspective, mesenchymal stromal cells (MSCs) are an interesting candidate because of their immunosuppressive and regenerative properties. Of importance, no other clinical studies have investigated their effects in allograft rejection and fibrosis. We performed a safety and feasibility study in kidney allograft recipients to whom two intravenous infusions (1 million cells per kilogram) of autologous bone marrow (BM) MSCs were given, when a protocol renal biopsy at 4 weeks or 6 months showed signs of rejection and/or an increase in interstitial fibrosis/tubular atrophy (IF/TA). Six patients received MSC infusions. Clinical and immune monitoring was performed up to 24 weeks after MSC infusions. MSCs fulfilled the release criteria, infusions were well‐tolerated, and no treatment‐related serious adverse events were reported. In two recipients with allograft rejection, we had a clinical indication to perform surveillance biopsies and are able to report on the potential effects of MSCs in rejection. Although maintenance immunosuppression remained unaltered, there was a resolution of tubulitis without IF/TA in both patients. Additionally, three patients developed an opportunistic viral infection, and five of the six patients displayed a donor‐specific downregulation of the peripheral blood mononuclear cell proliferation assay, not reported in patients without MSC treatment. Autologous BM MSC treatment in transplant recipients with subclinical rejection and IF/TA is clinically feasible and safe, and the findings are suggestive of systemic immunosuppression.
ABSTRACT
The complement system, and specifically C5a, is involved in renal ischemia‐reperfusion (IR) injury. The 2 receptors for complement anaphylatoxin C5a (C5aR1 and C5aR2) are expressed on ...leukocytes as well as on renal epithelium. Extensive evidence shows that C5aR1 inhibition protects kidneys from IR injury; however, the role of C5aR2 in IR injury is less clear as initial studies proposed the hypothesis that C5aR2 functions as a decoy receptor. By Using wild‐type, C5aR1‐/‐, and C5aR2‐/‐ mice in a model of renal IR injury, we found that a deficiency of either of these receptors protected mice from renal IR injury. Surprisingly, C5aR2‐/‐ mice were most protected and had lower creatinine levels and reduced acute tubular necrosis. Next, an in vivo migration study demonstrated that leukocyte chemotaxis was unaffected in C5aR2‐/‐ mice, whereas neutrophil activation was reduced by C5aR2 deficiency. To further investigate the contribution of renal cell‐expressed C5aR2 vs. leukocyte‐expressed C5aR2 to renal IR injury, bone marrow chimeras were created. Our data show that both renal cell‐expressed C5aR2 and leukocyte‐expressed C5aR2 mediate IR‐induced renal dysfunction. These studies reveal the importance of C5aR2 in renal IR injury. They further show that C5aR2 is a functional receptor, rather than a decoy receptor, and may provide a new target for intervention.—Poppelaars, F., van Werkhoven, M. B., Kotimaa, J., Veldhuis, Z. J., Ausema, A., Broeren, S. G. M., Damman, J., Hempel, J. C., Leuvenink, H. G. D., Daha, M. R., van Son, W. J., van Kooten, C., van Os, R. P., Hillebrands, J.‐L., Seelen, M. A. Critical role for complement receptor C5aR2 in the pathogenesis of renal ischemia‐reperfusion injury. FASEB J. 31, 3193–3204 (2017). www.fasebj.org
Dendritic cells (DCs) and complement are both key members of the innate and adaptive immune response. Recent experimental mouse models have shown that production of alternative pathway (AP) ...components by DCs strongly affects their ability to activate and regulate T‐cell responses. In this study we investigated the production and regulation of properdin (fP) and factor H (fH) both integral regulators of the AP, by DCs and tolerogenic DCs (tolDCs). Both fP and fH were produced by DCs, with significantly higher levels of both AP components produced by tolDCs. Upon activation with IFN‐γ both cells increased fH production, while simultaneously decreasing production of fP. IL‐27, a member of the IL‐12 family, increased fH, but production of fP remained unaffected. The functional capacity of fP and fH produced by DCs and tolDCs was confirmed by their ability to bind C3b. Inhibition of fH production by DCs resulted in a greater ability to induce allogenic CD4+ T‐cell proliferation. In contrast, inhibition of fP production led to a significantly reduced allostimulatory capacity. In summary, this study shows that production of fP and fH by DCs, differentially regulates their immunogenicity, and that the local cytokine environment can profoundly affect the production of fP and fH.
Dendritic cells produce properdin and factor H, key opposing regulators of the alternative pathway of complement. IFN‐γ stimulation decreased DC derived properdin while simultaneously increasing factor H production. siRNA inhibition of DC derived properdin reduced T cell proliferation, while silencing DC factor H promoted T cell expansion and IFN‐γ production.
PDF
